1. Field of the Invention
The present invention relates to providing communications between networks, and more particularly to a mobile application part (MAP) message processing system and method for interworking between heterogeneous networks which adhere to different communications protocols.
2. Background of the Related Art
A next-generation mobile communication service has been proposed to provide extended multimedia service by integrating a voice-oriented, first-generation analog mobile phone and a voice and low-speed data transmission-available second-generation digital mobile phone.
A representative example is an IMT-2000 service which provides a multimedia communication service such as the Internet and an image transmission through a system combining a wired network, a wireless network and a satellite network. The IMT-2000 service also provides a global roaming service that allows a user to use a mobile communication service with one terminal even though the user moves to anywhere in the world on the basis of using the common frequency and a single technology standard.
In order to provide such a global roaming service, the whole world should use the same technical method and a frequency of the same band. However, as for the current technology method of the next-generation mobile communication service, like the initial intention of an international standard organization that was willing to make a single technology standard, an asynchronous method has been adopted as a standard in Europe, while a multicarrier technology and ANSI-MAP has been adopted as a standard in the North America.
The GSM-MAP is based on the standard of a global system for mobile communication (GSM) 09.02 or 29.002 on a European telecommunication standards Institute (ETSI)/3rd generation partnership project (3GPP), while the ANSI-MAP is based on the interim standard-41 (IS-41) standard of the American National Standards Institute (ANSI)/3GPP2.
Accordingly, in order to implement a global roaming service for a next-generation mobile communication service in such an environment, a network interworking technology is required between the ANSI-MAP-based core network (referred to as ‘ANSI’ network, hereinafter) and GSM-MAP-based core network (referred to as ‘GSM’ network, hereinafter).
FIG. 1 is a drawing illustrating a MAP message flow in the ANSI network in accordance with a conventional art, and FIG. 2 is drawing illustrating a MAP message flow in the GSM network in accordance with a conventional art. The ANSI network of the GSM network transmits and processes a MAP message in order to manage a location of a mobile station, process a mobile call, and provide various supplementary services related to a call processing. MAP messages are defined by a remote operation, and are transmitted between network elements using a service provided by lower layer protocols.
The lowest tree levels of the SS7 architecture, referred to as the message transfer part (MTP), provide a reliable but connectionless (datagram style) service for routing messages through the SS7 network. MTP level 1 (MTP1) allows the use of any digital-type interface. MTP level 2 (MTP2) provides the functions necessary for basic error detection and correction. This protocol is concerned only with the reliable delivery of signal units between two exchanges or SPs. There is no consideration outside of the signaling link and it has no knowledge of the final destination. The MTP level 3 (MTP 3) protocol has the responsibility of transporting messages between SPs. There are two broad functional categories preformed by this layer network management and message handling.
MTP does not provide the complete set of functions and services specified in the OSI layer 1-3, most notably in the areas of addressing and connection-oriented service. In the 1984 version of SS7, an additional module was added, which resides in level four of SS7 and which is known as the signaling connection control part SCCP).
One major enhancement provided by the SCCP is its expanded addressing functionality. The SCCP supplements MTP addressing by defining an additional field called the subsystem number (SSN), which consists of local addressing information used to identify SCCP users at each node. The combination of OPC plus SSN forms the calling party address, and the DPC plus SSN number is the called party address.
Another SCCP enhancement is its ability to use global titles as addresses. A global title is a special address, such as an 800 number, that does not provide information usable for routing. SCCP is the protocol that performs the global title translation.
The transaction capabilities application part (TCAP), first introduced in 1988, provides the mechanisms for transaction-oriented (as opposed to connection-oriented) applications and functions. TCAP provides a general purpose, remote operation function for SS7. It provides the capability for an application at one node to invoke the execution of an operation at another node and to receive the results from that remote process. TCAP was originally designed to support queries into databases, although its role can include additional functions.
TCAP comprises two protocol sublayers called the transaction sublayer (TSL) and the component sublayer (CSL). The TSL is the lower TCAP sublayer and it defines how the transaction or dialogue will take place, that is, what will be the context in which the remote operation will take place. There are two types of dialogues: the unstructured dialogue, that is a one-way communication in which the remote peer processes our message but does not send any response back; and the structured dialogue, which is analogous to a virtual connection where queries produce responses.
The CSL is the upper TCAP sublayer which comprises two handlers called dialogue handling block (DHA) and component handling block (CHA). The CHA handles a message's called component portion and DHA handles a message's called dialogue portion as the actual messages that are contained in the TSL messages.
There are four types of CSL dialogue portions: AARQ (dialogue request), AARE, (dialogue response), ABRT (dialogue abort), AUDT (dialogue UNI). The dialogue portion allows TC-users to exchange user information outside components. The protocol associated with these exchanges is fully in charge of the TC-user and is identified by the application context name parameter. User data which is a part of dialogue portion can also be exchanged using the user information parameter.
There are four types of CSL component portions: invoke (to request a remote operation), return result (containing the response of the requested operation), return error (indicating some kind of error), and reject (indicating some kind of syntax error). Invoke and return have single and multiple message versions (in case a unique message is not enough).
The TCAP services are provided to an upper user application which is called the application service element (ASE), responsible for providing the information that a specific application needs.
A network element in the conventional next-generation mobile communication network is constructed only with the MAP of an environment that is based on one of the ANSI-MAP standard or the GSM-MAP standard Therefore, the conventional next-generation mobile communication network can process only MAP messages which conform to the same standard. Further, the conventional network fails to perfectly implement the global roaming service, which is the target of the next-generation mobile communication service. That is, the conventional next-generation mobile communication network can implement the global roaming service only if the messages they receive conform to a compatible standard specification.